Effects of Soil Erosion and Sediment Deposition on Surface Water Quality: A Case Study of Otamiri River

J. C. Osuagwu, A. N. Nwachukwu, H. U. Nwoke, K. C. Agbo


Soil erosion involves detachment soil particles and transportation by run-off with subsequent deposition of the sediments in river courses and land depressions. The otamiri river  is one of the main rivers in Imo state, Nigeria and the source for Owerri water scheme. The river runs from Egbu in Owerri, Imo state to Ozuzu in Etche, Rivers State from where it flows to the Atlantic Ocean. It is a major receiver of sediments from numerous gullies in the watershed. The objective of study was to analyse the nature and extent of the effects of the sediments inflow on the major quality parameters of the river with a view to making recommendations on sustainable preservation of the river. Water samples were collected during runoff inflows at two different locations (A and B) simultaneously for physical and biochemical tests.  Location A was near the source at Egbu while B is a location downstream near discharge point of a major gully. The results showed marked fluctuation in quality between samples from location A and B. .  Measured values of Ph, hardness, Iron, chloride, BOD, TSS and TDS indicated 30.8%, 88.9%, 50%, 60% , 176%, 94.5% and 84.4% differences respectively.  The value of pollution index computed for sample B is 2.43 while that of Sample A is 1.22. This is an indication of a higher level of level of pollution of sample B relative to Sample A. The results indicate that sediments adversely affected surface water quality.



Key Words: Run-off, erosion, sediments, gully, pollution.

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